The invention concerns a microtome comprising a knife holding device and a specimen holding device, wherein the specimen holding device has a first drive device for performing a cutting movement and the specimen holding device or the knife holding device has a second drive device for performing a feed movement.
Microtomes of that kind are known per se in various different forms. For example the prospectus ‘The MICROM HM 350 S’ from MICROM International, 69190 Waldorf, discloses a microtome in which it is possible to eliminate a hand wheel for manual upward and downward movement of the specimen holding device, that is to say for manually performing a cutting movement. The above-mentioned hand wheel is replaced by an operating element which is for example a rotary knob. By way of an incremental generator the rotary knob controls the movements of the specimen holding device, which correspond to the rotary knob. In that known rotational microtome therefore the rotary knob simulates the vertical cutting movement, that is to say the vertical upward and downward movement of the specimen holding device in relation to a base frame of the microtome.
DE 199 11 163 C1 discloses a microtome in which the cutting operation is performed by a relative movement between a cutting knife and a specimen. A drive comprising a drive motor, a control circuit and a hand wheel is provided for producing that relative movement. The hand wheel is connected to an encoder which, upon rotation of the hand wheel, delivers corresponding signals to the control circuit. The drive motor is then suitably actuated by way of that control circuit. The drive is blocked, in the absence of encoder signals. That known microtome therefore has a hand wheel which, upon a rotary movement, delivers signals to the control circuit by way of an encoder. The hand wheel is therefore suitable for carrying out an operating mode corresponding to the standard mode of the microtome according to the invention. There however it is the hand wheel that is actuated and not an operating element; in addition that microtome also has a second control mode in which, by depressing the operating element, the first drive device provided for performing the cutting movement performs a permanent cutting movement of respectively constant speed and amplitude and thus a corresponding continuous cutting function. For that purpose the known microtome has a keyboard, a rotary regulator and switches. The keyboard serves for numerical input, the rotary regulator serves for continuously variable inputs and the switches serve for the input of given switch positions and operating conditions. In that known microtome therefore there are both a hand wheel and also an operating desk with a multiplicity of keys and switches, that is to say operating elements, so that the operating comfort suffers from serious deficiencies. In addition the switches in that microtome do not have a regulating function. The regulating function is first achieved by the additional rotary regulator. In that case therefore, in addition to the hand wheel, the arrangement still requires three different keys or switches, that is to say groups of operating elements, which has a correspondingly detrimental effect on operating comfort. Consequently the design concept of that known microtome corresponds to the well-known configurations having a hand wheel for manual operation, with start/stop keys or buttons for the motor function and a further regulating knob for speed regulation.
DE 199 11 005 A1 discloses a method of controlling a disk microtome in which parameters which are adjustable by motor means are set by way of a control circuit. In that arrangement predetermined reference values for the motor-adjustable parameters are continuously compared to ascertained actual values of the motor-adjustable parameters. Control signals for actuation of the motor-adjustable parameters are formed from the difference between the reference values and the actual values. An external operating desk is connected to the control circuit by way of a control line and a hand wheel, with an associated encoder, is connected to the circuit by way of a second control line. Therefore, that known microtome also has both a hand wheel and also an operating desk so that the level of operating comfort leaves something to be desired in a similar way to the operating comfort of the above-discussed microtome disclosed in DE 199 11 163 C1. A similar consideration also applies in regard to the microtome which is known from DE 31 27 266 A1 and which has an operating and control arrangement connected to a drive and a microprocessor. The speed of rotation of the drive shaft of the drive can be influenced by means of the microprocessor and the operating and control arrangement. An advance selection option for setting the desired cutting region length is provided on an advance transmission of that microtome. Setting is effected by way of a hand wheel. Depending on the respective setting of the hand wheel, a greater or smaller advance movement of the preparation arm is implemented per revolution of the drive shaft. In this known microtome therefore there are both an operating unit and also a hand wheel so that—as in the above-discussed microtomes—the operating comfort still leaves something to be desired.
The object of the invention is to provide a microtome of the kind set forth in the opening part of this specification, with improved operating comfort.